Macrophage proliferation in atherosclerosis

aDepartment of Metabolic Medicine, and bDepartment of Biochemistry, Kumamoto University School of Medicine, Honjo 1-1-1, Kumamoto 860-8556, Japan

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Abstract

Oxidized LDL can induce an increase in intracellular calcium concentration and the activation of protein kinase C in mouse peritoneal macrophages. The activation of protein kinase C leads to the release into the culture medium of granulocyte-macrophage colony-stimulating factor, which plays a priming role in oxidized LDL-induced macrophage proliferation. The expression of granulocyte-macrophage colony-stimulating factor in macrophages by oxidized LDL is positively regulated in the 5′-flanking region of granulocyte-macrophage colony-stimulating factor gene from sequence −169 to −160, but negatively regulated from −91 to −82. Granulocyte-macrophage colony-stimulating factor released by oxidized LDL from macrophages induces proliferation in autocrine or paracrine fashion via the activation of phosphatidylinositol 3-kinase. The capacity of oxidized LDL to induce macrophage proliferation in vitro may be involved in the enhanced progression of atherosclerosis in vivo.